Amazing Radio Show

October 22, 2009

I love the show Radio Lab from WNYC. Jad Abumrad and Robert Krulwich explore science topics with a cool attitude and an edgy sound mix. Last week they ran a show called “New Normal”. It’s a must-listen for any Robert Sapolsky fan.

If you haven’t heard of Robert Sapolsky and have any interest in Evolutionay Biology, Human Origins, Animal Behavior, life in the African bush or the effect of stress on people and animals run out and get a copy of A Primate’s Memoir: A Neuroscientist’s Unconventional Life Among the Baboons.

Actually, you should read the book and then do the radio show because the interview with Robert Sapolsky gives away the wrenching ending to A Primate’s Memoir. Anyone who has read this book – you must listen to this show. There is an incredibly uplifting revelation about how things have worked out for Sapolsky’s baboon troupe.

The 3rd segment is about the Balyaev fox breeding experiments where Dr. Balyaev bred tame foxes in 10 generations and how that changed the animals.

Direct link to download the RadioLab MP3 podcast.

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BARF Mythology

January 20, 2009

I came accross an interesting article by Steven E. Crane that argues against Biologically Appropriate Raw Food (BARF) feeding for dogs. This article takes fundamental issue with the logic of BARF because the premise that wolves are dogs and that BARF is a natural wolfe diet appropriate for all dogs is wrong on several levels.

Crane’s anti-BARF argument, in a nutshell, is that dogs are not wolves any more than people are chimpanzees. Even if dogs were wolves; wolves, unlike cats, are not obligate carnivores. The order Carnivora is defined by dentition, not dietary habits. (The giant panda, for instance, is a member of the order Carnivora but subsists on a largely herbivorous diet.) Wolves are omnivores with a penchant for meat and, in any case, wild wolves live lives that are, to use the words of Thomas Hobbes, nasty, brutish and short.

A very small segment of pet owners have accepted the opinions of a vocal fringe minority of individuals who are currently proponents of feeding raw foods. The diet is commonly called the BARF diet, (Bones And Raw Food). Individuals within this group often make unsubstantiated claims that sound plausible but are typically unsupported in fact. The barf diet is extolled based primarily upon several myths claimed to justify the feeding of this diet.  

Myth 1 – Claimed similarities between modern wild canids and the domestic dog, and thus modern domestic dogs therefore have identical genetic development and nutritional needs as wild canids.

Myth 2 – Claims of increased disease levels and shortened life spans in pet dogs versus claimed lack of disease and increased life spans in wild ancestral canids like wolves and coyotes.

Myth 3 – Claimed reduced levels of parasites.

Myth 4 – Claimed reduced levels of food intolerance, adverse reactions to foods, and or “allergies”.

Myth 5 – Claims that feeding “raw meaty bones” are good for domestic dogs.

Myth 6 – Claimed increased value of uncooked foods versus cooked foods and subsequent loss of trace micro-nutrients by the cooking process.

Popular discussion of BARF in the US is based to a large degree on myths promoted by superficial and hyperbolic promoters of one product or another, or those selling the latest version of video tapes, books, supplements, foods and other materials. Barfers’ typically denigrate any information that is derived from solid scientific studies as having been “tainted” by some supposed conspiracy of involvement between commercial pet food companies, veterinary teaching universities, the FDA, USDA, CDC, WHO, and any other evidence knowledge based organization. At the same time Barfers accept at face value opinions promoted by purveyors of Barf products and scaremongering media. No level of competence or proof is demanded of those who state facts in favor of Barf feeding; while multiple, peer reviewed published university research studies are often denigrated by Barfers’.

This paper seeks to examine some of these myths. As a confirmed Barfer once noted, the decision to feed BARF is an emotional one, not a science based decision. As we shall see, making decisions based on emotions can lead one astray.

continue reading…

Last summer I saw a DVD from the PBS show Nature called “Dogs that Changed the World” and also read the book of one of the contributing scientists. One of the really interesting parts of the miniseries was a discussion of the breeding program of a Russian scientist named Dmitri Belyaev which began in 1948.

Belyaev’s breeding program was designed to create a tame breed of silver foxes. As an aside, this was thought to have commercial implications because the raising of silver foxes in captivity for the Russian fur industry is difficult because the foxes are vicious.

What Belyaev did was select for a single behavior. The foxes that were least aggressive and avoidant were bred together. The result of this breeding program was that in just a few generations. Within a relatively small number of generations, by selecting only for temperament, Belyaev had created a very different stain of fox:

  • They became dog-like and friendly with people
  • Some of the tame foxes developed drop-ears
  • The musky “fox smell” dissapeared
  • They became white and black like border collies
  • The pups begin responding to sounds 2 days earlier than wild type pups
  • The pups open their eyes a day earlier than wild type pups
  • Delayed onset of adult corticosteriod hormones levels (~8 months of age instead of 2-4 months of age)
  • Their social behavior changed
  • They wagged their tails when happy
  • They began to bark and vocalize like dogs
  • The tame foxes tended to have shorter tails and shorter legs
  • Curled and double-curled tails developed
  • Overbite and underbite developed
  • The tame females came into estrus (heat) more frequently

The amazing takeaway point is that selecting for behavior and nothing else yielded dramatic cascade of apparently unrelated physical changes in the animals.

Incidentally, the physical changes make the fur of the tame foxes commercially useless. My understanding is that Belyaev has not been able to breed a tame fox that has the correct pelt for the fur industry and so the tame fox is not commercially viable.

Top 10 Evolution Articles

December 29, 2008

A rundown of some great evolution articles from New Scientist that are well worth reading:

 How trees changed the world

It’s only when you try to imagine a world without trees that you realise how much we take them for granted. Yet 450 million years ago there was no such thing as a tree: few plants grew more than a centimetre tall. Between then and now, things happened to give another dimension to plant growth and to create the diversity we see today.

Reclaiming the peppered moth for science

The peppered moth used to be the textbook example of evolution in action. Then, about a decade ago, creationists began an orchestrated a campaign to discredit it – and with it the entire edifice of evolution. Now biologists are fighting to take it back…

Uncovering the evolution of the bacterial flagellum

The whip-like tail of some bacteria has become the cause célèbre of the “intelligent design” movement and a focal point in science’s ongoing struggle against unreason. It doesn’t seem possible to come up with one via Darwin’s “numerous, successive, slight modifications”, they say. Now science is coming up with an answer…

Evolution: What missing link?

The fossil record used to be thought of as a patchy and unreliable record of evolutionary change. Today, that record is much more dependable. When it comes to “transitional fossils” – those that bridge the gap between major groups of organisms – we now have some excellent examples.

Evolution: 24 myths and misconceptions

Evolution is perhaps the best known yet least understood of all scientific theories. Here, NewScientist.com, seeks out the facts behind common misunderstandings that have grown up around “the blind watchmaker”.

Rewriting Darwin: The new non-genetic inheritance

We resemble our parents and can fall prey to the same diseases mainly because we inherit their genes. Yet there is another form of inheritance that does not rely on genes, one that allows characteristics to be passed on that are acquired during a person’s lifetime…

The Ordivician: Life’s second big bang

The Cambrian period, starting about 540 million years ago, is famous for the appearance of all but one of the types of creatures we see around us today. Yet in terms of new species this period cannot hold a candle to a little-known explosion of life called the Great Ordivician Biodiversification Event.

Vestigial organs: Remnants of evolution

From goosebumps to wisdom teeth, vestigial organs have long perplexed biologists. What was their original purpose and what happened to make them redundant? NewScientist.com presents its top five vestigial organs and explains how they differ from male nipples.

Viruses: The unsung heroes of evolution

Viruses are often seen solely as carriers of death and disease. In the light of genomics, however, they are being seen as critical evolutionary players. Far from being a biological afterthought, they may be the most creative genetic entities we know of.

Freedom from selection lets genes get creative

Natural selection is seen as a tough master, constantly applying pressure to improve the fit between an organism and its niche. Yet some researchers believe that when the pressure of natural selection lifts, genomes go wandering and unexpected effects can arise. To see the impact, he argues, we have to look no further than ourselves…

Lamarck and Darwin

Jean-Baptiste Lamarck was an 18th century French naturlist who developed the first coherent theory of organic evolution. That is to say, he developed a testable scientific theory of how organisms evolve into other oganisms through time without divine intervention. Lamarck incorporated into his theory the common belief of the day that organisms can inherit the acuired characteristics of their parents. He belived in something he called l’influence des circonstances or the Adaptive Force which causes organisms to adapt to changes in their environment. Those acquired adaptations are then passed on to the offspring of the organism through sexual reproduction. 

Jean-Baptiste Lamarck and Charles Darwin

Jean-Baptiste Lamarck and Charles Darwin

Under Lamarck’s theory, for example, a blacksmith could develop a right arm that was stronger and larger than his left arm. The son of the blacksmith would inherit this characteristic and develop it further and so on and so forth until you get a race of blacksmiths with one giant arm. This is nonsense. An organism cannot pass on acquired traits to its offspring.

In the 19th century, Charles Darwin, showed that evolution can happen without the deus ex machina of an invisible adaptive force. A population of organisms has random variation in traits. All of the organisms cannot survive and reproduce. Only some of the animals successfully reproduce themselves (for whatever reason) and, in the case of species that reproduce sexually, only some of the possible mating combinations occur. This Natural Selection operating on the population is the engine that drives evolution, rather than an Adaptive Force. The other feature of Darwinian evolution is “descent with modification” or the idea that sometimes the offspring in the new generation have a characteristic not found in the parents. We usually call descent with modification  mutation. Mutation and differential reproductive success are the forces that drive evolution.

The thing is, though, that Lamarckian inheritance is very intuitive to people. I often observe people speaking about selection and evolution, especially with respect to purebred dogs, in Lamarckian terms without realizing that they are doing it. Whenever we think about how purebred dogs have changed through time, we need to stop and remind ourselves that animals cannot transmit acquired characteristics to their offspring. We change the characteristics of breeding populations only by selecting which specimens will breed forward to the next generation. Nothing else matters.

Evolution is driven by differential reproductive success. Traits acquired during the life of an animal cannot be passed on to their offspring.